1. Field of the Invention
The present invention relates to an air pipe mounted for moderation of a variation in internal pressure on a housing or the like which is of a closed construction of a lighting fixture for a vehicle.
2. Description of the Prior Art
An example of a structure of a conventional air pipe 31 of this kind is shown in FIG. 3. This air pipe 31 is formed of an elastic material such as rubber and molded by using a mold. A plurality of projections 32 are provided in a zigzag fashion on an inner diameter portion 31a in order to prevent rain water or the like from entering from outside.
However, even if the air pipe 31 is formed of an elastic material such as rubber which is easily deformed, a portion of the projection 32 is forcibly drawn by great force during molding. This gives rises to a problem in that a service life of a mold is extremely shortened. There is a further problem in that a defect such as a breakage occurs in the portion of the projection 32, resulting in a lowering of yield of the product. These problems should be solved.